Robothon, the annual robotics competition and exhibition staged by the Seattle Robotics Society, has a FaceBook page you're going to want to "like".
Robothon 2012 is scheduled for Saturday, June 2nd at the Armory Center House in Seattle. A full day of exciting events are scheduled starting at 10 am. Attendance, and participation, is totally free.
The competitions include Robo-Magellan, Line Following, Line Maze, and Mini Sumo, with great prizes for the winning robots in each competition.